I've searched for good guides for hours now, but with no luck. I want to create a custom Page Type with custom fields. There are 100s of guides on how to create that using some of the popular plugins and it seems to work just fine.
The thing is, I might occasionally need to create a much more advanced custom page type and I've found no guide that helps me extend a custom page type with my own PHP code.
My lack of luck finding guides on how to manually extend page types might be because it's a lot better to create a plugin for it, it might be because I'm horrible at using Google or it might be because people just don't do that manually since everything can be achieved easily with plugins if you're familiar enough with them.
I'm well aware that the answer might be "It depends on what you want to do", so I'll just make up a scenario:
I need to create a custom page type with the usual basic stuff: Headline, Content WYSIWYG, Categories, Thumbnail and Excerpt, this CPT will also need another area, let's say that it needs an area to create timetables for school classes, those timetables needs to be sortable by drag and drop and other slick JS stuff.
In this scenario - would I create a plugin that manually includes the ordinary page stuff and adds the extra functionality? Or would I create a CPT and somehow manually extend it with the extra functionality I need.
Sorry if I could have made it shorter, I'm very new to WP and struggleing to get a hold of all the correct jargon :)